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Excessive noise on VHF radio when Transmitting

 
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hgmckay



Joined: 23 May 2006
Posts: 397

PostPosted: Tue Jun 14, 2016 1:40 pm    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

Gentlemen,

I have a noise problem on the VHF radio system in my plane when I attempt to transmit. In fact The other day while flying through Class C airspace the approach controller was telling me that my transmission was broken and had so much noise he could hardly understand what I was saying. I also hear the noise in my headphones when I transmit, not when receiving.

I have visually checked all the ground connections on the plane and they are clear of corrosion and are tight. While on the ground with the engine not running the radio transmission is fine with no problems. The problem only occurs when the engine is running. The noise sounds like the frequency of the rotating generator on the back of the engine which is a Rotax 912 UL. The audible frequency can be heard to vary with the engine rpm. It is “dirty” noise. My radio is a panel mounted ICOM IC-A200. I also have two 10,000 mF capacitors connected in parallel between the voltage regulator and ground as noise filters. I have visually checked the two capacitors, and they seem to be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI 121 using a quarter wave ground plane. I have had no problems with this system for ten years.

Here are the specifics:
Aircraft Allegro 2000 LSA
Engine Rotax 912 UL
TSN 741 hrs
Radio ICOM IC-A200
Antenna Comant VHF CI 121

Any and all advice as to how to identify what is causing the problem and how to correct it would be appreciated.

Hugh G. McKay III, P.E.
N661WW
email hgmckay(at)bellsouth.net


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peteohms



Joined: 31 Oct 2007
Posts: 224
Location: Leander, TX

PostPosted: Tue Jun 14, 2016 2:14 pm    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

Do you have a cigarette lighter USB adapter plugged in? They can cause this.
Pete

On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:
Quote:
Gentlemen,

I have a noise problem on the VHF radio system in my plane when I attempt to transmit. In fact The other day while flying through Class C airspace the approach controller was telling me that my transmission was broken and had so much noise he could hardly understand what I was saying. I also hear the noise in my headphones when I transmit, not when receiving.

I have visually checked all the ground connections on the plane and they are clear of corrosion and are tight. While on the ground with the engine not running the radio transmission is fine with no problems. The problem only occurs when the engine is running. The noise sounds like the frequency of the rotating generator on the back of the engine which is a Rotax 912 UL. The audible frequency can be heard to vary with the engine rpm. It is “dirty” noise. My radio is a panel mounted ICOM IC-A200. I also have two 10,000 mF capacitors connected in parallel between the voltage regulator and ground as noise filters. I have visually checked the two capacitors, and they seem to be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI 121 using a quarter wave ground plane. I have had no problems with this system for ten years.

Here are the specifics:
Aircraft Allegro 2000 LSA
Engine Rotax 912 UL
TSN 741 hrs
Radio ICOM IC-A200
Antenna Comant VHF CI 121

Any and all advice as to how to identify what is causing the problem and how to correct it would be appreciated.

Hugh G. McKay III, P.E.
N661WW
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)


<Hugh.vcf>


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Pete
Leander, TX
Kitfox III, 912ul, Grove
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rlborger(at)mac.com
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PostPosted: Tue Jun 14, 2016 3:00 pm    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

Hugh,
Do you perchance have an ANR headset?

With my Lightspeed Zulu 2, if the ANR isn’t operating, my transmissions are hopelessly garbled and noisy. First sign that the batteries in the ANR unit are dying is when the tower can’t understand my transmission due to the engine noise in the cockpit.

Another source of noise I’ve run into is with some plug=in USB power sources. Some seem OK others generate a lot of electrical noise.

Blue skies & tailwinds,Bob BorgerEuropa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP3705 Lynchburg Dr.Corinth, TX 76208-5331Cel: 817-992-1117rlborger(at)mac.com (rlborger(at)mac.com)

On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:
Gentlemen,

I have a noise problem on the VHF radio system in my plane when I attempt to transmit. In fact The other day while flying through Class C airspace the approach controller was telling me that my transmission was broken and had so much noise he could hardly understand what I was saying. I also hear the noise in my headphones when I transmit, not when receiving.

I have visually checked all the ground connections on the plane and they are clear of corrosion and are tight. While on the ground with the engine not running the radio transmission is fine with no problems. The problem only occurs when the engine is running. The noise sounds like the frequency of the rotating generator on the back of the engine which is a Rotax 912 UL. The audible frequency can be heard to vary with the engine rpm. It is “dirty” noise. My radio is a panel mounted ICOM IC-A200. I also have two 10,000 mF capacitors connected in parallel between the voltage regulator and ground as noise filters. I have visually checked the two capacitors, and they seem to be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI 121 using a quarter wave ground plane. I have had no problems with this system for ten years.

Here are the specifics:
Aircraft Allegro 2000 LSA
Engine Rotax 912 UL
TSN 741 hrs
Radio ICOM IC-A200
Antenna Comant VHF CI 121

Any and all advice as to how to identify what is causing the problem and how to correct it would be appreciated.

Hugh G. McKay III, P.E.N661WWemail hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)

<Hugh.vcf>


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hgmckay



Joined: 23 May 2006
Posts: 397

PostPosted: Tue Jun 14, 2016 3:13 pm    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

Pete,

My GPS unit is powered for a cigarette lighter plug, but I have been doing this for ten years w/o a problem.

Hugh G. McKay III, P.E. Fellow, L.M. ASCE
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net
http://www.wwegeo.com

From: Pete Christensen (pchristensen10(at)austin.rr.com)
Sent: Tuesday, June 14, 2016 6:13 PM
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: Re: Excessive noise on VHF radio when Transmitting



Do you have a cigarette lighter USB adapter plugged in? They can cause this.

Pete

On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:
Quote:
Gentlemen,

I have a noise problem on the VHF radio system in my plane when I attempt to transmit. In fact The other day while flying through Class C airspace the approach controller was telling me that my transmission was broken and had so much noise he could hardly understand what I was saying. I also hear the noise in my headphones when I transmit, not when receiving.

I have visually checked all the ground connections on the plane and they are clear of corrosion and are tight. While on the ground with the engine not running the radio transmission is fine with no problems. The problem only occurs when the engine is running. The noise sounds like the frequency of the rotating generator on the back of the engine which is a Rotax 912 UL. The audible frequency can be heard to vary with the engine rpm. It is “dirty” noise. My radio is a panel mounted ICOM IC-A200. I also have two 10,000 mF capacitors connected in parallel between the voltage regulator and ground as noise filters. I have visually checked the two capacitors, and they seem to be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI 121 using a quarter wave ground plane. I have had no problems with this system for ten years.

Here are the specifics:
Aircraft Allegro 2000 LSA
Engine Rotax 912 UL
TSN 741 hrs
Radio ICOM IC-A200
Antenna Comant VHF CI 121

Any and all advice as to how to identify what is causing the problem and how to correct it would be appreciated.

Hugh G. McKay III, P.E.
N661WW
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)


<Hugh.vcf>


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Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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hgmckay



Joined: 23 May 2006
Posts: 397

PostPosted: Tue Jun 14, 2016 3:16 pm    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

Robert,

My head sets are not ANR headsets. My GPS is powered from a cigarette lighter plug, but it is not a USB.

Hugh G. McKay III, P.E. Fellow, L.M. ASCE
Senior Consultant
Worldwide Engineering Inc.
4090 North NC Hwy. 16
Denver, NC 28037

Ph. 704-661-8271
Fax 704-483-5466
email hgmckay(at)bellsouth.net
http://www.wwegeo.com

From: Robert Borger (rlborger(at)mac.com)
Sent: Tuesday, June 14, 2016 6:59 PM
To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)
Subject: Re: Excessive noise on VHF radio when Transmitting


Hugh,
Do you perchance have an ANR headset?

With my Lightspeed Zulu 2, if the ANR isn’t operating, my transmissions are hopelessly garbled and noisy. First sign that the batteries in the ANR unit are dying is when the tower can’t understand my transmission due to the engine noise in the cockpit.

Another source of noise I’ve run into is with some plug=in USB power sources. Some seem OK others generate a lot of electrical noise.

Blue skies & tailwinds,Bob BorgerEuropa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP3705 Lynchburg Dr.Corinth, TX 76208-5331Cel: 817-992-1117rlborger(at)mac.com (rlborger(at)mac.com)

On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:

Gentlemen,

I have a noise problem on the VHF radio system in my plane when I attempt to transmit. In fact The other day while flying through Class C airspace the approach controller was telling me that my transmission was broken and had so much noise he could hardly understand what I was saying. I also hear the noise in my headphones when I transmit, not when receiving.

I have visually checked all the ground connections on the plane and they are clear of corrosion and are tight. While on the ground with the engine not running the radio transmission is fine with no problems. The problem only occurs when the engine is running. The noise sounds like the frequency of the rotating generator on the back of the engine which is a Rotax 912 UL. The audible frequency can be heard to vary with the engine rpm. It is “dirty” noise. My radio is a panel mounted ICOM IC-A200. I also have two 10,000 mF capacitors connected in parallel between the voltage regulator and ground as noise filters. I have visually checked the two capacitors, and they seem to be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI 121 using a quarter wave ground plane. I have had no problems with this system for ten years.

Here are the specifics:
Aircraft Allegro 2000 LSA
Engine Rotax 912 UL
TSN 741 hrs
Radio ICOM IC-A200
Antenna Comant VHF CI 121

Any and all advice as to how to identify what is causing the problem and how to correct it would be appreciated.

Hugh G. McKay III, P.E.
N661WW
email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)


<Hugh.vcf>


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Don Maxwell



Joined: 04 Sep 2014
Posts: 4

PostPosted: Thu Jun 16, 2016 5:43 am    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

That's what I think, too. I have a Zulu 2 and an original Zulu. The ANR is good enough that when the batteries die the noise level in my ears is really disconcerting.  But no one has ever complained about the quality of my transmissions.  It's possible that they hear more of the engine noise--I don't know about that--but it couldn't be any louder than when I used to wear passive headsets in the same airplane.

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lcfitt3(at)gmail.com
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PostPosted: Thu Jun 16, 2016 7:04 am    Post subject: Excessive noise on VHF radio when Transmitting Reply with quote

I have been watching this thread and hesitated joining in as my experience is minimal, but recently I had periods of severe noise in the headsets.  I don't know if it was in the transmission as my flying is all non towered.  What I found was when charging my tablet through a USB running from a plug in adapter, the adapter had inadequate noise suppression circuitry designed into the dc/dc converter.  I also found that the noise interference was a broadcast RF noise rather than being sent through the wiring.
Lowell Fitt On Jun 16, 2016 6:47 AM, "Don Maxwell" <DonMaxwell(at)abstractconcreteworks.com (DonMaxwell(at)abstractconcreteworks.com)> wrote:
Quote:
That's what I think, too. I have a Zulu 2 and an original Zulu. The ANR is good enough that when the batteries die the noise level in my ears is really disconcerting.  But no one has ever complained about the quality of my transmissions.  It's possible that they hear more of the engine noise--I don't know about that--but it couldn't be any louder than when I used to wear passive headsets in the same airplane.



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